Whether the statement, “a bacterial replication fork is asymmetrical because it contains two DNA polymerase molecules that are structurally distinct” is correct. Introduction : DNA is the blueprint of life and contains genetic information. Replication of DNA is semiconservative. The integrity of DNA is essential for life, and if there is any damage to it, it will lead to mutation and disease. DNA can undergo spontaneous damage from water every day. DNA damage may be caused due to environment insults, and DNA replication errors. However, cells have DNA repair mechanisms that detect damage and repair it. The cells that are not repaired undergo programmed cell death. If the damage accumulates due to some mutations, it would cause diseases such as cancer.

Question

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Answer 1

Question

Chapter 6, Problem 7Q

A.

Summary Introduction

To determine: Whether the statement, “a bacterial replication fork is asymmetrical because it contains two DNA polymerase molecules that are structurally distinct” is correct.

Introduction: DNA is the blueprint of life and contains genetic information. Replication of DNA is semiconservative. The integrity of DNA is essential for life, and if there is any damage to it, it will lead to mutation and disease. DNA can undergo spontaneous damage from water every day. DNA damage may be caused due to environment insults, and DNA replication errors. However, cells have DNA repair mechanisms that detect damage and repair it. The cells that are not repaired undergo programmed cell death. If the damage accumulates due to some mutations, it would cause diseases such as cancer.

A.

Expert Solution

Answer to Problem 7Q

The given statement is incorrect.

Explanation of Solution

During DNA replication, one strand that runs in the direction of bacterial replication fork (5′-3′) is continuous and is referred as the leading strand. The other strand is made in fragments known as Okazaki fragments and is known as the lagging strand. On these strands, DNA polymerase enzyme molecules catalyze the synthesis of DNA. All the DNA polymerase molecules are structurally identical and thus, the given statement is incorrect. The replication fork is asymmetrical, as the lagging strand is synthesized in fragments and then they are ligate together by DNA ligase.

B.

Summary Introduction

To determine: Whether the statement, “Okazaki fragments are removed by a nuclease that degrades RNA” is correct.

Introduction: DNA is the blueprint of life and contains genetic information. Replication of DNA is semiconservative. The integrity of DNA is essential for life, and if there is any damage to it, it will lead to mutation and disease. DNA can undergo spontaneous damage from water every day. DNA damage may be caused due to environment insults, and DNA replication errors. However, cells have DNA repair mechanisms that detect damage and repair it. The cells that are not repaired undergo programmed cell death. If the damage accumulates due to some mutations, it would cause diseases such as cancer.

B.

Expert Solution

Answer to Problem 7Q

The given statement is incorrect.

Explanation of Solution

When new DNA strands are formed, RNA primers are removed by nuclease enzyme and gaps are filled with DNA by DNA polymerase enzyme. The gaps between Okazaki fragments of DNA are connected by DNA ligase enzyme. Thus, the statement is incorrect as only RNA primers are removed by nuclease (RNase).

C.

Summary Introduction

To determine: Whether the statement, “the error rate of DNA replication is reduced both by proofreading by DNA polymerase and by DNA mismatch repair” is correct.

Introduction: DNA is the blueprint of life and contains genetic information. Replication of DNA is semiconservative. The integrity of DNA is essential for life, and if there is any damage to it, it will lead to mutation and disease. DNA can undergo spontaneous damage from water every day. DNA damage may be caused due to environment insults, and DNA replication errors. However, cells have DNA repair mechanisms that detect damage and repair it. The cells that are not repaired undergo programmed cell death. If the damage accumulates due to some mutations, it would cause diseases such as cancer.

C.

Expert Solution

Answer to Problem 7Q

The given statement is correct.

Explanation of Solution

When new DNA strands are formed, RNA primers are removed and gaps are filled with DNA by DNA polymerase enzyme. DNA polymerase enzyme adds DNA nucleotides to an existing strand with high fidelity. It proofreads the DNA strand to check for any errors or mismatch with an error rate of 10⁷ polymerized nucleotides. Also, mismatch repair system recognizes and repairs 99 % errors during DNA replication. Thus, the statement is correct as proofreading by DNA polymerase enzyme and, DNA mismatch repair system reduces the error rate of DNA replication.

D.

Summary Introduction

To determine: Whether the statement, “in the absence of DNA repair, genes are unstable” is correct.

Introduction: DNA is the blueprint of life and contains genetic information. Replication of DNA is semiconservative. The integrity of DNA is essential for life, and if there is any damage to it, it will lead to mutation and disease. DNA can undergo spontaneous damage from water every day. DNA damage may be caused due to environment insults, and DNA replication errors. However, cells have DNA repair mechanisms that detect damage and repair it. The cells that are not repaired undergo programmed cell death. If the damage accumulates due to some mutations, it would cause diseases such as cancer.

D.

Expert Solution

Answer to Problem 7Q

The given statement is correct.

Explanation of Solution

DNA is the blueprint of life and contains genetic information. The integrity of DNA is essential for life, and if there is any damage to it, it will lead to mutation and disease. DNA damage may be caused due to environment insults, and DNA replication occurs. However, cells have DNA repair mechanisms that detect damage and repair it. The cells undergo programmed cell death, that is, apoptosis. If DNA repair systems are absent, then the damage would accumulate due to some mutations, it would cause diseases such as cancer. Many genes would become inactive, thus the statement is correct.

E.

Summary Introduction

To determine: Whether the statement, “none of the aberrant bases formed by deamination occur naturally in DNA” is correct.

Introduction: DNA is the blueprint of life and contains genetic information. Replication of DNA is semiconservative. The integrity of DNA is essential for life, and if there is any damage to it, it will lead to mutation and disease. DNA can undergo spontaneous damage from water every day. DNA damage may be caused due to environment insults, and DNA replication errors. However, cells have DNA repair mechanisms that detect damage and repair it. The cells that are not repaired undergo programmed cell death. If the damage accumulates due to some mutations, it would cause diseases such as cancer.

E.

Expert Solution

Answer to Problem 7Q

The given statement is correct.

Explanation of Solution

DNA damage occurs continuously in cells every day. Deamination is the spontaneous hydrolysis of nucleotide base cytosine to uracil. It is a spontaneous variation and can occur on either of the two DNA strands. Base excision repair (BER) system in body repairs it. If nucleotide bases formed by deamination occurred naturally, then the repair enzymes would not be able to recognize the damage. Thus, the statement is correct that damaged nucleotides by deamination do not occur naturally in DNA.

F.

Summary Introduction

To determine: Whether the statement, “cancer can result from the accumulation of mutations in somatic cells” is correct.

Introduction: DNA is the blueprint of life and contains genetic information. Replication of DNA is semiconservative. The integrity of DNA is essential for life, and if there is any damage to it, it will lead to mutation and disease. DNA can undergo spontaneous damage from water every day. DNA damage may be caused due to environment insults, and DNA replication errors. However, cells have DNA repair mechanisms that detect damage and repair it. The cells that are not repaired undergo programmed cell death. If the damage accumulates due to some mutations, it would cause diseases such as cancer.

F.

Expert Solution

Answer to Problem 7Q

The given statement is correct.

Explanation of Solution

DNA damage occurs continuously in cells every day. It may be caused due to environment insults, and DNA replication occurs. However, cells have DNA repair mechanisms that detect damage and repair it. The cells that are not repaired undergo programmed cell death. If the damage accumulates due to some mutations, it would cause diseases such as cancer.

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Answer 2

Question

Chapter 6, Problem 7Q

A.

Summary Introduction

To determine: Whether the statement, “a bacterial replication fork is asymmetrical because it contains two DNA polymerase molecules that are structurally distinct” is correct.

Introduction: DNA is the blueprint of life and contains genetic information. Replication of DNA is semiconservative. The integrity of DNA is essential for life, and if there is any damage to it, it will lead to mutation and disease. DNA can undergo spontaneous damage from water every day. DNA damage may be caused due to environment insults, and DNA replication errors. However, cells have DNA repair mechanisms that detect damage and repair it. The cells that are not repaired undergo programmed cell death. If the damage accumulates due to some mutations, it would cause diseases such as cancer.

A.

Expert Solution

Answer to Problem 7Q

The given statement is incorrect.

Explanation of Solution

During DNA replication, one strand that runs in the direction of bacterial replication fork (5′-3′) is continuous and is referred as the leading strand. The other strand is made in fragments known as Okazaki fragments and is known as the lagging strand. On these strands, DNA polymerase enzyme molecules catalyze the synthesis of DNA. All the DNA polymerase molecules are structurally identical and thus, the given statement is incorrect. The replication fork is asymmetrical, as the lagging strand is synthesized in fragments and then they are ligate together by DNA ligase.

B.

Summary Introduction

To determine: Whether the statement, “Okazaki fragments are removed by a nuclease that degrades RNA” is correct.

Introduction: DNA is the blueprint of life and contains genetic information. Replication of DNA is semiconservative. The integrity of DNA is essential for life, and if there is any damage to it, it will lead to mutation and disease. DNA can undergo spontaneous damage from water every day. DNA damage may be caused due to environment insults, and DNA replication errors. However, cells have DNA repair mechanisms that detect damage and repair it. The cells that are not repaired undergo programmed cell death. If the damage accumulates due to some mutations, it would cause diseases such as cancer.

B.

Expert Solution

Answer to Problem 7Q

The given statement is incorrect.

Explanation of Solution

When new DNA strands are formed, RNA primers are removed by nuclease enzyme and gaps are filled with DNA by DNA polymerase enzyme. The gaps between Okazaki fragments of DNA are connected by DNA ligase enzyme. Thus, the statement is incorrect as only RNA primers are removed by nuclease (RNase).

C.

Summary Introduction

To determine: Whether the statement, “the error rate of DNA replication is reduced both by proofreading by DNA polymerase and by DNA mismatch repair” is correct.

Introduction: DNA is the blueprint of life and contains genetic information. Replication of DNA is semiconservative. The integrity of DNA is essential for life, and if there is any damage to it, it will lead to mutation and disease. DNA can undergo spontaneous damage from water every day. DNA damage may be caused due to environment insults, and DNA replication errors. However, cells have DNA repair mechanisms that detect damage and repair it. The cells that are not repaired undergo programmed cell death. If the damage accumulates due to some mutations, it would cause diseases such as cancer.

C.

Expert Solution

Answer to Problem 7Q

The given statement is correct.

Explanation of Solution

When new DNA strands are formed, RNA primers are removed and gaps are filled with DNA by DNA polymerase enzyme. DNA polymerase enzyme adds DNA nucleotides to an existing strand with high fidelity. It proofreads the DNA strand to check for any errors or mismatch with an error rate of 10⁷ polymerized nucleotides. Also, mismatch repair system recognizes and repairs 99 % errors during DNA replication. Thus, the statement is correct as proofreading by DNA polymerase enzyme and, DNA mismatch repair system reduces the error rate of DNA replication.

D.

Summary Introduction

To determine: Whether the statement, “in the absence of DNA repair, genes are unstable” is correct.

Introduction: DNA is the blueprint of life and contains genetic information. Replication of DNA is semiconservative. The integrity of DNA is essential for life, and if there is any damage to it, it will lead to mutation and disease. DNA can undergo spontaneous damage from water every day. DNA damage may be caused due to environment insults, and DNA replication errors. However, cells have DNA repair mechanisms that detect damage and repair it. The cells that are not repaired undergo programmed cell death. If the damage accumulates due to some mutations, it would cause diseases such as cancer.

D.

Expert Solution

Answer to Problem 7Q

The given statement is correct.

Explanation of Solution

DNA is the blueprint of life and contains genetic information. The integrity of DNA is essential for life, and if there is any damage to it, it will lead to mutation and disease. DNA damage may be caused due to environment insults, and DNA replication occurs. However, cells have DNA repair mechanisms that detect damage and repair it. The cells undergo programmed cell death, that is, apoptosis. If DNA repair systems are absent, then the damage would accumulate due to some mutations, it would cause diseases such as cancer. Many genes would become inactive, thus the statement is correct.

E.

Summary Introduction

To determine: Whether the statement, “none of the aberrant bases formed by deamination occur naturally in DNA” is correct.

Introduction: DNA is the blueprint of life and contains genetic information. Replication of DNA is semiconservative. The integrity of DNA is essential for life, and if there is any damage to it, it will lead to mutation and disease. DNA can undergo spontaneous damage from water every day. DNA damage may be caused due to environment insults, and DNA replication errors. However, cells have DNA repair mechanisms that detect damage and repair it. The cells that are not repaired undergo programmed cell death. If the damage accumulates due to some mutations, it would cause diseases such as cancer.

E.

Expert Solution

Answer to Problem 7Q

The given statement is correct.

Explanation of Solution

DNA damage occurs continuously in cells every day. Deamination is the spontaneous hydrolysis of nucleotide base cytosine to uracil. It is a spontaneous variation and can occur on either of the two DNA strands. Base excision repair (BER) system in body repairs it. If nucleotide bases formed by deamination occurred naturally, then the repair enzymes would not be able to recognize the damage. Thus, the statement is correct that damaged nucleotides by deamination do not occur naturally in DNA.

F.

Summary Introduction

To determine: Whether the statement, “cancer can result from the accumulation of mutations in somatic cells” is correct.

Introduction: DNA is the blueprint of life and contains genetic information. Replication of DNA is semiconservative. The integrity of DNA is essential for life, and if there is any damage to it, it will lead to mutation and disease. DNA can undergo spontaneous damage from water every day. DNA damage may be caused due to environment insults, and DNA replication errors. However, cells have DNA repair mechanisms that detect damage and repair it. The cells that are not repaired undergo programmed cell death. If the damage accumulates due to some mutations, it would cause diseases such as cancer.

F.

Expert Solution

Answer to Problem 7Q

The given statement is correct.

Explanation of Solution

DNA damage occurs continuously in cells every day. It may be caused due to environment insults, and DNA replication occurs. However, cells have DNA repair mechanisms that detect damage and repair it. The cells that are not repaired undergo programmed cell death. If the damage accumulates due to some mutations, it would cause diseases such as cancer.

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Answer 3

Question

Chapter 6, Problem 7Q

A.

Summary Introduction

To determine: Whether the statement, “a bacterial replication fork is asymmetrical because it contains two DNA polymerase molecules that are structurally distinct” is correct.

Introduction: DNA is the blueprint of life and contains genetic information. Replication of DNA is semiconservative. The integrity of DNA is essential for life, and if there is any damage to it, it will lead to mutation and disease. DNA can undergo spontaneous damage from water every day. DNA damage may be caused due to environment insults, and DNA replication errors. However, cells have DNA repair mechanisms that detect damage and repair it. The cells that are not repaired undergo programmed cell death. If the damage accumulates due to some mutations, it would cause diseases such as cancer.

A.

Expert Solution

Answer to Problem 7Q

The given statement is incorrect.

Explanation of Solution

During DNA replication, one strand that runs in the direction of bacterial replication fork (5′-3′) is continuous and is referred as the leading strand. The other strand is made in fragments known as Okazaki fragments and is known as the lagging strand. On these strands, DNA polymerase enzyme molecules catalyze the synthesis of DNA. All the DNA polymerase molecules are structurally identical and thus, the given statement is incorrect. The replication fork is asymmetrical, as the lagging strand is synthesized in fragments and then they are ligate together by DNA ligase.

B.

Summary Introduction

To determine: Whether the statement, “Okazaki fragments are removed by a nuclease that degrades RNA” is correct.

Introduction: DNA is the blueprint of life and contains genetic information. Replication of DNA is semiconservative. The integrity of DNA is essential for life, and if there is any damage to it, it will lead to mutation and disease. DNA can undergo spontaneous damage from water every day. DNA damage may be caused due to environment insults, and DNA replication errors. However, cells have DNA repair mechanisms that detect damage and repair it. The cells that are not repaired undergo programmed cell death. If the damage accumulates due to some mutations, it would cause diseases such as cancer.

B.

Expert Solution

Answer to Problem 7Q

The given statement is incorrect.

Explanation of Solution

When new DNA strands are formed, RNA primers are removed by nuclease enzyme and gaps are filled with DNA by DNA polymerase enzyme. The gaps between Okazaki fragments of DNA are connected by DNA ligase enzyme. Thus, the statement is incorrect as only RNA primers are removed by nuclease (RNase).

C.

Summary Introduction

To determine: Whether the statement, “the error rate of DNA replication is reduced both by proofreading by DNA polymerase and by DNA mismatch repair” is correct.

Introduction: DNA is the blueprint of life and contains genetic information. Replication of DNA is semiconservative. The integrity of DNA is essential for life, and if there is any damage to it, it will lead to mutation and disease. DNA can undergo spontaneous damage from water every day. DNA damage may be caused due to environment insults, and DNA replication errors. However, cells have DNA repair mechanisms that detect damage and repair it. The cells that are not repaired undergo programmed cell death. If the damage accumulates due to some mutations, it would cause diseases such as cancer.

C.

Expert Solution

Answer to Problem 7Q

The given statement is correct.

Explanation of Solution

When new DNA strands are formed, RNA primers are removed and gaps are filled with DNA by DNA polymerase enzyme. DNA polymerase enzyme adds DNA nucleotides to an existing strand with high fidelity. It proofreads the DNA strand to check for any errors or mismatch with an error rate of 10⁷ polymerized nucleotides. Also, mismatch repair system recognizes and repairs 99 % errors during DNA replication. Thus, the statement is correct as proofreading by DNA polymerase enzyme and, DNA mismatch repair system reduces the error rate of DNA replication.

D.

Summary Introduction

To determine: Whether the statement, “in the absence of DNA repair, genes are unstable” is correct.

Introduction: DNA is the blueprint of life and contains genetic information. Replication of DNA is semiconservative. The integrity of DNA is essential for life, and if there is any damage to it, it will lead to mutation and disease. DNA can undergo spontaneous damage from water every day. DNA damage may be caused due to environment insults, and DNA replication errors. However, cells have DNA repair mechanisms that detect damage and repair it. The cells that are not repaired undergo programmed cell death. If the damage accumulates due to some mutations, it would cause diseases such as cancer.

D.

Expert Solution

Answer to Problem 7Q

The given statement is correct.

Explanation of Solution

DNA is the blueprint of life and contains genetic information. The integrity of DNA is essential for life, and if there is any damage to it, it will lead to mutation and disease. DNA damage may be caused due to environment insults, and DNA replication occurs. However, cells have DNA repair mechanisms that detect damage and repair it. The cells undergo programmed cell death, that is, apoptosis. If DNA repair systems are absent, then the damage would accumulate due to some mutations, it would cause diseases such as cancer. Many genes would become inactive, thus the statement is correct.

E.

Summary Introduction

To determine: Whether the statement, “none of the aberrant bases formed by deamination occur naturally in DNA” is correct.

Introduction: DNA is the blueprint of life and contains genetic information. Replication of DNA is semiconservative. The integrity of DNA is essential for life, and if there is any damage to it, it will lead to mutation and disease. DNA can undergo spontaneous damage from water every day. DNA damage may be caused due to environment insults, and DNA replication errors. However, cells have DNA repair mechanisms that detect damage and repair it. The cells that are not repaired undergo programmed cell death. If the damage accumulates due to some mutations, it would cause diseases such as cancer.

E.

Expert Solution

Answer to Problem 7Q

The given statement is correct.

Explanation of Solution

DNA damage occurs continuously in cells every day. Deamination is the spontaneous hydrolysis of nucleotide base cytosine to uracil. It is a spontaneous variation and can occur on either of the two DNA strands. Base excision repair (BER) system in body repairs it. If nucleotide bases formed by deamination occurred naturally, then the repair enzymes would not be able to recognize the damage. Thus, the statement is correct that damaged nucleotides by deamination do not occur naturally in DNA.

F.

Summary Introduction

To determine: Whether the statement, “cancer can result from the accumulation of mutations in somatic cells” is correct.

Introduction: DNA is the blueprint of life and contains genetic information. Replication of DNA is semiconservative. The integrity of DNA is essential for life, and if there is any damage to it, it will lead to mutation and disease. DNA can undergo spontaneous damage from water every day. DNA damage may be caused due to environment insults, and DNA replication errors. However, cells have DNA repair mechanisms that detect damage and repair it. The cells that are not repaired undergo programmed cell death. If the damage accumulates due to some mutations, it would cause diseases such as cancer.

F.

Expert Solution

Answer to Problem 7Q

The given statement is correct.

Explanation of Solution

DNA damage occurs continuously in cells every day. It may be caused due to environment insults, and DNA replication occurs. However, cells have DNA repair mechanisms that detect damage and repair it. The cells that are not repaired undergo programmed cell death. If the damage accumulates due to some mutations, it would cause diseases such as cancer.

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Answer 4

Question

Chapter 6, Problem 7Q

A.

Summary Introduction

To determine: Whether the statement, “a bacterial replication fork is asymmetrical because it contains two DNA polymerase molecules that are structurally distinct” is correct.

Introduction: DNA is the blueprint of life and contains genetic information. Replication of DNA is semiconservative. The integrity of DNA is essential for life, and if there is any damage to it, it will lead to mutation and disease. DNA can undergo spontaneous damage from water every day. DNA damage may be caused due to environment insults, and DNA replication errors. However, cells have DNA repair mechanisms that detect damage and repair it. The cells that are not repaired undergo programmed cell death. If the damage accumulates due to some mutations, it would cause diseases such as cancer.

A.

Expert Solution

Answer to Problem 7Q

The given statement is incorrect.

Explanation of Solution

During DNA replication, one strand that runs in the direction of bacterial replication fork (5′-3′) is continuous and is referred as the leading strand. The other strand is made in fragments known as Okazaki fragments and is known as the lagging strand. On these strands, DNA polymerase enzyme molecules catalyze the synthesis of DNA. All the DNA polymerase molecules are structurally identical and thus, the given statement is incorrect. The replication fork is asymmetrical, as the lagging strand is synthesized in fragments and then they are ligate together by DNA ligase.

B.

Summary Introduction

To determine: Whether the statement, “Okazaki fragments are removed by a nuclease that degrades RNA” is correct.

Introduction: DNA is the blueprint of life and contains genetic information. Replication of DNA is semiconservative. The integrity of DNA is essential for life, and if there is any damage to it, it will lead to mutation and disease. DNA can undergo spontaneous damage from water every day. DNA damage may be caused due to environment insults, and DNA replication errors. However, cells have DNA repair mechanisms that detect damage and repair it. The cells that are not repaired undergo programmed cell death. If the damage accumulates due to some mutations, it would cause diseases such as cancer.

B.

Expert Solution

Answer to Problem 7Q

The given statement is incorrect.

Explanation of Solution

When new DNA strands are formed, RNA primers are removed by nuclease enzyme and gaps are filled with DNA by DNA polymerase enzyme. The gaps between Okazaki fragments of DNA are connected by DNA ligase enzyme. Thus, the statement is incorrect as only RNA primers are removed by nuclease (RNase).

C.

Summary Introduction

To determine: Whether the statement, “the error rate of DNA replication is reduced both by proofreading by DNA polymerase and by DNA mismatch repair” is correct.

Introduction: DNA is the blueprint of life and contains genetic information. Replication of DNA is semiconservative. The integrity of DNA is essential for life, and if there is any damage to it, it will lead to mutation and disease. DNA can undergo spontaneous damage from water every day. DNA damage may be caused due to environment insults, and DNA replication errors. However, cells have DNA repair mechanisms that detect damage and repair it. The cells that are not repaired undergo programmed cell death. If the damage accumulates due to some mutations, it would cause diseases such as cancer.

C.

Expert Solution

Answer to Problem 7Q

The given statement is correct.

Explanation of Solution

When new DNA strands are formed, RNA primers are removed and gaps are filled with DNA by DNA polymerase enzyme. DNA polymerase enzyme adds DNA nucleotides to an existing strand with high fidelity. It proofreads the DNA strand to check for any errors or mismatch with an error rate of 10⁷ polymerized nucleotides. Also, mismatch repair system recognizes and repairs 99 % errors during DNA replication. Thus, the statement is correct as proofreading by DNA polymerase enzyme and, DNA mismatch repair system reduces the error rate of DNA replication.

D.

Summary Introduction

To determine: Whether the statement, “in the absence of DNA repair, genes are unstable” is correct.

Introduction: DNA is the blueprint of life and contains genetic information. Replication of DNA is semiconservative. The integrity of DNA is essential for life, and if there is any damage to it, it will lead to mutation and disease. DNA can undergo spontaneous damage from water every day. DNA damage may be caused due to environment insults, and DNA replication errors. However, cells have DNA repair mechanisms that detect damage and repair it. The cells that are not repaired undergo programmed cell death. If the damage accumulates due to some mutations, it would cause diseases such as cancer.

D.

Expert Solution

Answer to Problem 7Q

The given statement is correct.

Explanation of Solution

DNA is the blueprint of life and contains genetic information. The integrity of DNA is essential for life, and if there is any damage to it, it will lead to mutation and disease. DNA damage may be caused due to environment insults, and DNA replication occurs. However, cells have DNA repair mechanisms that detect damage and repair it. The cells undergo programmed cell death, that is, apoptosis. If DNA repair systems are absent, then the damage would accumulate due to some mutations, it would cause diseases such as cancer. Many genes would become inactive, thus the statement is correct.

E.

Summary Introduction

To determine: Whether the statement, “none of the aberrant bases formed by deamination occur naturally in DNA” is correct.

Introduction: DNA is the blueprint of life and contains genetic information. Replication of DNA is semiconservative. The integrity of DNA is essential for life, and if there is any damage to it, it will lead to mutation and disease. DNA can undergo spontaneous damage from water every day. DNA damage may be caused due to environment insults, and DNA replication errors. However, cells have DNA repair mechanisms that detect damage and repair it. The cells that are not repaired undergo programmed cell death. If the damage accumulates due to some mutations, it would cause diseases such as cancer.

E.

Expert Solution

Answer to Problem 7Q

The given statement is correct.

Explanation of Solution

DNA damage occurs continuously in cells every day. Deamination is the spontaneous hydrolysis of nucleotide base cytosine to uracil. It is a spontaneous variation and can occur on either of the two DNA strands. Base excision repair (BER) system in body repairs it. If nucleotide bases formed by deamination occurred naturally, then the repair enzymes would not be able to recognize the damage. Thus, the statement is correct that damaged nucleotides by deamination do not occur naturally in DNA.

F.

Summary Introduction

To determine: Whether the statement, “cancer can result from the accumulation of mutations in somatic cells” is correct.

Introduction: DNA is the blueprint of life and contains genetic information. Replication of DNA is semiconservative. The integrity of DNA is essential for life, and if there is any damage to it, it will lead to mutation and disease. DNA can undergo spontaneous damage from water every day. DNA damage may be caused due to environment insults, and DNA replication errors. However, cells have DNA repair mechanisms that detect damage and repair it. The cells that are not repaired undergo programmed cell death. If the damage accumulates due to some mutations, it would cause diseases such as cancer.

F.

Expert Solution

Answer to Problem 7Q

The given statement is correct.

Explanation of Solution

DNA damage occurs continuously in cells every day. It may be caused due to environment insults, and DNA replication occurs. However, cells have DNA repair mechanisms that detect damage and repair it. The cells that are not repaired undergo programmed cell death. If the damage accumulates due to some mutations, it would cause diseases such as cancer.

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Answer 5

Chapter 6, Problem 7Q

A.

Summary Introduction

To determine: Whether the statement, “a bacterial replication fork is asymmetrical because it contains two DNA polymerase molecules that are structurally distinct” is correct.

Introduction: DNA is the blueprint of life and contains genetic information. Replication of DNA is semiconservative. The integrity of DNA is essential for life, and if there is any damage to it, it will lead to mutation and disease. DNA can undergo spontaneous damage from water every day. DNA damage may be caused due to environment insults, and DNA replication errors. However, cells have DNA repair mechanisms that detect damage and repair it. The cells that are not repaired undergo programmed cell death. If the damage accumulates due to some mutations, it would cause diseases such as cancer.

A.

Expert Solution

Answer to Problem 7Q

The given statement is incorrect.

Explanation of Solution

During DNA replication, one strand that runs in the direction of bacterial replication fork (5′-3′) is continuous and is referred as the leading strand. The other strand is made in fragments known as Okazaki fragments and is known as the lagging strand. On these strands, DNA polymerase enzyme molecules catalyze the synthesis of DNA. All the DNA polymerase molecules are structurally identical and thus, the given statement is incorrect. The replication fork is asymmetrical, as the lagging strand is synthesized in fragments and then they are ligate together by DNA ligase.

B.

Summary Introduction

To determine: Whether the statement, “Okazaki fragments are removed by a nuclease that degrades RNA” is correct.

Introduction: DNA is the blueprint of life and contains genetic information. Replication of DNA is semiconservative. The integrity of DNA is essential for life, and if there is any damage to it, it will lead to mutation and disease. DNA can undergo spontaneous damage from water every day. DNA damage may be caused due to environment insults, and DNA replication errors. However, cells have DNA repair mechanisms that detect damage and repair it. The cells that are not repaired undergo programmed cell death. If the damage accumulates due to some mutations, it would cause diseases such as cancer.

B.

Expert Solution

Answer to Problem 7Q

The given statement is incorrect.

Explanation of Solution

When new DNA strands are formed, RNA primers are removed by nuclease enzyme and gaps are filled with DNA by DNA polymerase enzyme. The gaps between Okazaki fragments of DNA are connected by DNA ligase enzyme. Thus, the statement is incorrect as only RNA primers are removed by nuclease (RNase).

C.

Summary Introduction

To determine: Whether the statement, “the error rate of DNA replication is reduced both by proofreading by DNA polymerase and by DNA mismatch repair” is correct.

Introduction: DNA is the blueprint of life and contains genetic information. Replication of DNA is semiconservative. The integrity of DNA is essential for life, and if there is any damage to it, it will lead to mutation and disease. DNA can undergo spontaneous damage from water every day. DNA damage may be caused due to environment insults, and DNA replication errors. However, cells have DNA repair mechanisms that detect damage and repair it. The cells that are not repaired undergo programmed cell death. If the damage accumulates due to some mutations, it would cause diseases such as cancer.

C.

Expert Solution

Answer to Problem 7Q

The given statement is correct.

Explanation of Solution

When new DNA strands are formed, RNA primers are removed and gaps are filled with DNA by DNA polymerase enzyme. DNA polymerase enzyme adds DNA nucleotides to an existing strand with high fidelity. It proofreads the DNA strand to check for any errors or mismatch with an error rate of 10⁷ polymerized nucleotides. Also, mismatch repair system recognizes and repairs 99 % errors during DNA replication. Thus, the statement is correct as proofreading by DNA polymerase enzyme and, DNA mismatch repair system reduces the error rate of DNA replication.

D.

Summary Introduction

To determine: Whether the statement, “in the absence of DNA repair, genes are unstable” is correct.

Introduction: DNA is the blueprint of life and contains genetic information. Replication of DNA is semiconservative. The integrity of DNA is essential for life, and if there is any damage to it, it will lead to mutation and disease. DNA can undergo spontaneous damage from water every day. DNA damage may be caused due to environment insults, and DNA replication errors. However, cells have DNA repair mechanisms that detect damage and repair it. The cells that are not repaired undergo programmed cell death. If the damage accumulates due to some mutations, it would cause diseases such as cancer.

D.

Expert Solution

Answer to Problem 7Q

The given statement is correct.

Explanation of Solution

DNA is the blueprint of life and contains genetic information. The integrity of DNA is essential for life, and if there is any damage to it, it will lead to mutation and disease. DNA damage may be caused due to environment insults, and DNA replication occurs. However, cells have DNA repair mechanisms that detect damage and repair it. The cells undergo programmed cell death, that is, apoptosis. If DNA repair systems are absent, then the damage would accumulate due to some mutations, it would cause diseases such as cancer. Many genes would become inactive, thus the statement is correct.

E.

Summary Introduction

To determine: Whether the statement, “none of the aberrant bases formed by deamination occur naturally in DNA” is correct.

Introduction: DNA is the blueprint of life and contains genetic information. Replication of DNA is semiconservative. The integrity of DNA is essential for life, and if there is any damage to it, it will lead to mutation and disease. DNA can undergo spontaneous damage from water every day. DNA damage may be caused due to environment insults, and DNA replication errors. However, cells have DNA repair mechanisms that detect damage and repair it. The cells that are not repaired undergo programmed cell death. If the damage accumulates due to some mutations, it would cause diseases such as cancer.

E.

Expert Solution

Answer to Problem 7Q

The given statement is correct.

Explanation of Solution

DNA damage occurs continuously in cells every day. Deamination is the spontaneous hydrolysis of nucleotide base cytosine to uracil. It is a spontaneous variation and can occur on either of the two DNA strands. Base excision repair (BER) system in body repairs it. If nucleotide bases formed by deamination occurred naturally, then the repair enzymes would not be able to recognize the damage. Thus, the statement is correct that damaged nucleotides by deamination do not occur naturally in DNA.

F.

Summary Introduction

To determine: Whether the statement, “cancer can result from the accumulation of mutations in somatic cells” is correct.

Introduction: DNA is the blueprint of life and contains genetic information. Replication of DNA is semiconservative. The integrity of DNA is essential for life, and if there is any damage to it, it will lead to mutation and disease. DNA can undergo spontaneous damage from water every day. DNA damage may be caused due to environment insults, and DNA replication errors. However, cells have DNA repair mechanisms that detect damage and repair it. The cells that are not repaired undergo programmed cell death. If the damage accumulates due to some mutations, it would cause diseases such as cancer.

F.

Expert Solution

Answer to Problem 7Q

The given statement is correct.

Explanation of Solution

DNA damage occurs continuously in cells every day. It may be caused due to environment insults, and DNA replication occurs. However, cells have DNA repair mechanisms that detect damage and repair it. The cells that are not repaired undergo programmed cell death. If the damage accumulates due to some mutations, it would cause diseases such as cancer.

Answer 6

Chapter 6, Problem 7Q

A.

Summary Introduction

To determine: Whether the statement, “a bacterial replication fork is asymmetrical because it contains two DNA polymerase molecules that are structurally distinct” is correct.

Introduction: DNA is the blueprint of life and contains genetic information. Replication of DNA is semiconservative. The integrity of DNA is essential for life, and if there is any damage to it, it will lead to mutation and disease. DNA can undergo spontaneous damage from water every day. DNA damage may be caused due to environment insults, and DNA replication errors. However, cells have DNA repair mechanisms that detect damage and repair it. The cells that are not repaired undergo programmed cell death. If the damage accumulates due to some mutations, it would cause diseases such as cancer.

A.

Expert Solution

Answer to Problem 7Q

The given statement is incorrect.

Explanation of Solution

During DNA replication, one strand that runs in the direction of bacterial replication fork (5′-3′) is continuous and is referred as the leading strand. The other strand is made in fragments known as Okazaki fragments and is known as the lagging strand. On these strands, DNA polymerase enzyme molecules catalyze the synthesis of DNA. All the DNA polymerase molecules are structurally identical and thus, the given statement is incorrect. The replication fork is asymmetrical, as the lagging strand is synthesized in fragments and then they are ligate together by DNA ligase.

Answer 7

Chapter 6, Problem 7Q

A.

Summary Introduction

To determine: Whether the statement, “a bacterial replication fork is asymmetrical because it contains two DNA polymerase molecules that are structurally distinct” is correct.

Introduction: DNA is the blueprint of life and contains genetic information. Replication of DNA is semiconservative. The integrity of DNA is essential for life, and if there is any damage to it, it will lead to mutation and disease. DNA can undergo spontaneous damage from water every day. DNA damage may be caused due to environment insults, and DNA replication errors. However, cells have DNA repair mechanisms that detect damage and repair it. The cells that are not repaired undergo programmed cell death. If the damage accumulates due to some mutations, it would cause diseases such as cancer.

Answer 8

A.

Expert Solution

Answer to Problem 7Q

The given statement is incorrect.

Answer 9

A.

Expert Solution

Answer 10

A.

Expert Solution

Answer 11

Expert Solution

Answer 12

Explanation of Solution

During DNA replication, one strand that runs in the direction of bacterial replication fork (5′-3′) is continuous and is referred as the leading strand. The other strand is made in fragments known as Okazaki fragments and is known as the lagging strand. On these strands, DNA polymerase enzyme molecules catalyze the synthesis of DNA. All the DNA polymerase molecules are structurally identical and thus, the given statement is incorrect. The replication fork is asymmetrical, as the lagging strand is synthesized in fragments and then they are ligate together by DNA ligase.

Answer 13

B.

Summary Introduction

To determine: Whether the statement, “Okazaki fragments are removed by a nuclease that degrades RNA” is correct.

Introduction: DNA is the blueprint of life and contains genetic information. Replication of DNA is semiconservative. The integrity of DNA is essential for life, and if there is any damage to it, it will lead to mutation and disease. DNA can undergo spontaneous damage from water every day. DNA damage may be caused due to environment insults, and DNA replication errors. However, cells have DNA repair mechanisms that detect damage and repair it. The cells that are not repaired undergo programmed cell death. If the damage accumulates due to some mutations, it would cause diseases such as cancer.

B.

Expert Solution

Answer to Problem 7Q

The given statement is incorrect.

Explanation of Solution

When new DNA strands are formed, RNA primers are removed by nuclease enzyme and gaps are filled with DNA by DNA polymerase enzyme. The gaps between Okazaki fragments of DNA are connected by DNA ligase enzyme. Thus, the statement is incorrect as only RNA primers are removed by nuclease (RNase).

Answer 14

B.

Summary Introduction

To determine: Whether the statement, “Okazaki fragments are removed by a nuclease that degrades RNA” is correct.

Introduction: DNA is the blueprint of life and contains genetic information. Replication of DNA is semiconservative. The integrity of DNA is essential for life, and if there is any damage to it, it will lead to mutation and disease. DNA can undergo spontaneous damage from water every day. DNA damage may be caused due to environment insults, and DNA replication errors. However, cells have DNA repair mechanisms that detect damage and repair it. The cells that are not repaired undergo programmed cell death. If the damage accumulates due to some mutations, it would cause diseases such as cancer.

Answer 15

B.

Expert Solution

Answer to Problem 7Q

The given statement is incorrect.

Answer 16

B.

Expert Solution

Answer 17

B.

Expert Solution

Answer 18

Expert Solution

Answer 19

Explanation of Solution

When new DNA strands are formed, RNA primers are removed by nuclease enzyme and gaps are filled with DNA by DNA polymerase enzyme. The gaps between Okazaki fragments of DNA are connected by DNA ligase enzyme. Thus, the statement is incorrect as only RNA primers are removed by nuclease (RNase).

Answer 20

C.

Summary Introduction

To determine: Whether the statement, “the error rate of DNA replication is reduced both by proofreading by DNA polymerase and by DNA mismatch repair” is correct.

Introduction: DNA is the blueprint of life and contains genetic information. Replication of DNA is semiconservative. The integrity of DNA is essential for life, and if there is any damage to it, it will lead to mutation and disease. DNA can undergo spontaneous damage from water every day. DNA damage may be caused due to environment insults, and DNA replication errors. However, cells have DNA repair mechanisms that detect damage and repair it. The cells that are not repaired undergo programmed cell death. If the damage accumulates due to some mutations, it would cause diseases such as cancer.

C.

Expert Solution

Answer to Problem 7Q

The given statement is correct.

Explanation of Solution

When new DNA strands are formed, RNA primers are removed and gaps are filled with DNA by DNA polymerase enzyme. DNA polymerase enzyme adds DNA nucleotides to an existing strand with high fidelity. It proofreads the DNA strand to check for any errors or mismatch with an error rate of 10⁷ polymerized nucleotides. Also, mismatch repair system recognizes and repairs 99 % errors during DNA replication. Thus, the statement is correct as proofreading by DNA polymerase enzyme and, DNA mismatch repair system reduces the error rate of DNA replication.

Answer 21

C.

Summary Introduction

To determine: Whether the statement, “the error rate of DNA replication is reduced both by proofreading by DNA polymerase and by DNA mismatch repair” is correct.

Introduction: DNA is the blueprint of life and contains genetic information. Replication of DNA is semiconservative. The integrity of DNA is essential for life, and if there is any damage to it, it will lead to mutation and disease. DNA can undergo spontaneous damage from water every day. DNA damage may be caused due to environment insults, and DNA replication errors. However, cells have DNA repair mechanisms that detect damage and repair it. The cells that are not repaired undergo programmed cell death. If the damage accumulates due to some mutations, it would cause diseases such as cancer.

Answer 22

C.

Expert Solution

Answer to Problem 7Q

The given statement is correct.

Answer 23

C.

Expert Solution

Answer 24

C.

Expert Solution

Answer 25

Expert Solution

Answer 26

Explanation of Solution

When new DNA strands are formed, RNA primers are removed and gaps are filled with DNA by DNA polymerase enzyme. DNA polymerase enzyme adds DNA nucleotides to an existing strand with high fidelity. It proofreads the DNA strand to check for any errors or mismatch with an error rate of 10⁷ polymerized nucleotides. Also, mismatch repair system recognizes and repairs 99 % errors during DNA replication. Thus, the statement is correct as proofreading by DNA polymerase enzyme and, DNA mismatch repair system reduces the error rate of DNA replication.

Answer 27

D.

Summary Introduction

To determine: Whether the statement, “in the absence of DNA repair, genes are unstable” is correct.

Introduction: DNA is the blueprint of life and contains genetic information. Replication of DNA is semiconservative. The integrity of DNA is essential for life, and if there is any damage to it, it will lead to mutation and disease. DNA can undergo spontaneous damage from water every day. DNA damage may be caused due to environment insults, and DNA replication errors. However, cells have DNA repair mechanisms that detect damage and repair it. The cells that are not repaired undergo programmed cell death. If the damage accumulates due to some mutations, it would cause diseases such as cancer.

D.

Expert Solution

Answer to Problem 7Q

The given statement is correct.

Explanation of Solution

DNA is the blueprint of life and contains genetic information. The integrity of DNA is essential for life, and if there is any damage to it, it will lead to mutation and disease. DNA damage may be caused due to environment insults, and DNA replication occurs. However, cells have DNA repair mechanisms that detect damage and repair it. The cells undergo programmed cell death, that is, apoptosis. If DNA repair systems are absent, then the damage would accumulate due to some mutations, it would cause diseases such as cancer. Many genes would become inactive, thus the statement is correct.

Answer 28

D.

Summary Introduction

To determine: Whether the statement, “in the absence of DNA repair, genes are unstable” is correct.

Introduction: DNA is the blueprint of life and contains genetic information. Replication of DNA is semiconservative. The integrity of DNA is essential for life, and if there is any damage to it, it will lead to mutation and disease. DNA can undergo spontaneous damage from water every day. DNA damage may be caused due to environment insults, and DNA replication errors. However, cells have DNA repair mechanisms that detect damage and repair it. The cells that are not repaired undergo programmed cell death. If the damage accumulates due to some mutations, it would cause diseases such as cancer.

Answer 29

D.

Expert Solution

Answer to Problem 7Q

The given statement is correct.

Answer 30

D.

Expert Solution

Answer 31

D.

Expert Solution

Answer 32

Expert Solution

Answer 33

Explanation of Solution

DNA is the blueprint of life and contains genetic information. The integrity of DNA is essential for life, and if there is any damage to it, it will lead to mutation and disease. DNA damage may be caused due to environment insults, and DNA replication occurs. However, cells have DNA repair mechanisms that detect damage and repair it. The cells undergo programmed cell death, that is, apoptosis. If DNA repair systems are absent, then the damage would accumulate due to some mutations, it would cause diseases such as cancer. Many genes would become inactive, thus the statement is correct.

Answer 34

E.

Summary Introduction

To determine: Whether the statement, “none of the aberrant bases formed by deamination occur naturally in DNA” is correct.

Introduction: DNA is the blueprint of life and contains genetic information. Replication of DNA is semiconservative. The integrity of DNA is essential for life, and if there is any damage to it, it will lead to mutation and disease. DNA can undergo spontaneous damage from water every day. DNA damage may be caused due to environment insults, and DNA replication errors. However, cells have DNA repair mechanisms that detect damage and repair it. The cells that are not repaired undergo programmed cell death. If the damage accumulates due to some mutations, it would cause diseases such as cancer.

E.

Expert Solution

Answer to Problem 7Q

The given statement is correct.

Explanation of Solution

DNA damage occurs continuously in cells every day. Deamination is the spontaneous hydrolysis of nucleotide base cytosine to uracil. It is a spontaneous variation and can occur on either of the two DNA strands. Base excision repair (BER) system in body repairs it. If nucleotide bases formed by deamination occurred naturally, then the repair enzymes would not be able to recognize the damage. Thus, the statement is correct that damaged nucleotides by deamination do not occur naturally in DNA.

Answer 35

E.

Summary Introduction

To determine: Whether the statement, “none of the aberrant bases formed by deamination occur naturally in DNA” is correct.

Introduction: DNA is the blueprint of life and contains genetic information. Replication of DNA is semiconservative. The integrity of DNA is essential for life, and if there is any damage to it, it will lead to mutation and disease. DNA can undergo spontaneous damage from water every day. DNA damage may be caused due to environment insults, and DNA replication errors. However, cells have DNA repair mechanisms that detect damage and repair it. The cells that are not repaired undergo programmed cell death. If the damage accumulates due to some mutations, it would cause diseases such as cancer.

Answer 36

E.

Expert Solution

Answer to Problem 7Q

The given statement is correct.

Answer 37

E.

Expert Solution

Answer 38

E.

Expert Solution

Answer 39

Expert Solution

Answer 40

Explanation of Solution

DNA damage occurs continuously in cells every day. Deamination is the spontaneous hydrolysis of nucleotide base cytosine to uracil. It is a spontaneous variation and can occur on either of the two DNA strands. Base excision repair (BER) system in body repairs it. If nucleotide bases formed by deamination occurred naturally, then the repair enzymes would not be able to recognize the damage. Thus, the statement is correct that damaged nucleotides by deamination do not occur naturally in DNA.

Answer 41

F.

Summary Introduction

To determine: Whether the statement, “cancer can result from the accumulation of mutations in somatic cells” is correct.

Introduction: DNA is the blueprint of life and contains genetic information. Replication of DNA is semiconservative. The integrity of DNA is essential for life, and if there is any damage to it, it will lead to mutation and disease. DNA can undergo spontaneous damage from water every day. DNA damage may be caused due to environment insults, and DNA replication errors. However, cells have DNA repair mechanisms that detect damage and repair it. The cells that are not repaired undergo programmed cell death. If the damage accumulates due to some mutations, it would cause diseases such as cancer.

F.

Expert Solution

Answer to Problem 7Q

The given statement is correct.

Explanation of Solution

DNA damage occurs continuously in cells every day. It may be caused due to environment insults, and DNA replication occurs. However, cells have DNA repair mechanisms that detect damage and repair it. The cells that are not repaired undergo programmed cell death. If the damage accumulates due to some mutations, it would cause diseases such as cancer.

Answer 42

F.

Summary Introduction

To determine: Whether the statement, “cancer can result from the accumulation of mutations in somatic cells” is correct.

Introduction: DNA is the blueprint of life and contains genetic information. Replication of DNA is semiconservative. The integrity of DNA is essential for life, and if there is any damage to it, it will lead to mutation and disease. DNA can undergo spontaneous damage from water every day. DNA damage may be caused due to environment insults, and DNA replication errors. However, cells have DNA repair mechanisms that detect damage and repair it. The cells that are not repaired undergo programmed cell death. If the damage accumulates due to some mutations, it would cause diseases such as cancer.

Answer 43

F.

Expert Solution

Answer to Problem 7Q

The given statement is correct.

Answer 44

F.

Expert Solution

Answer 45

F.

Expert Solution

Answer 46

Expert Solution

Answer 47

Explanation of Solution

DNA damage occurs continuously in cells every day. It may be caused due to environment insults, and DNA replication occurs. However, cells have DNA repair mechanisms that detect damage and repair it. The cells that are not repaired undergo programmed cell death. If the damage accumulates due to some mutations, it would cause diseases such as cancer.